The highest organ of the Economic Community of West African States (ECOWAS) is the

The highest organ of the Economic Community of West African States (ECOWAS) is the "Authority of Heads of State and Government". The Authority is made up of the Presidents or Heads of State of the ECOWAS member countries, and it provides the highest level of governance and decision-making in the organization. The Authority meets at least once a year and is responsible for the overall direction, coordination, and monitoring of ECOWAS policies and programs. It is also responsible for making major decisions, such as the adoption of new protocols, the appointment of the Executive Secretary of the Secretariat, and the establishment of new ECOWAS institutions. Therefore, the correct option to select in this scenario would be the "Authority of Heads of State and Government".